Joint CPUE standardization of the Pacific saury in the Northwest Pacific Ocean by using the spatio-temporal modelling approach

Reliable indices of population abundance are an important type of data for stock assessment. We applied a Vector-Autoregressive Spatio-Temporal Model (VAST) to conduct index standardization by using the joint CPUE (catch-per-unit-effort) data of the Pacific saury in the Northwest Pacific Ocean during 1994 and 2021. The results indicated that the annual standardized CPUE trend had a fluctuated pattern over studied periods, and the annual standardized CPUE value was at the lowest level below average (1994 - 2020) in 2021. The analysis we presented is generally applicable and should be considered as a standard tool in the CPUE standardization.